When sourcing bird whistles, material choice is critical for both sound quality and user safety. For plastic whistles, ensure they are made from BPA-free, non-toxic ABS plastic, especially since these are oral-contact products. For metal versions (often used for professional bird training), prioritize stainless steel or nickel-plated brass to prevent corrosion from saliva. If sourcing water bird whistles (ceramic), verify that the glaze is lead-free and cadmium-free to comply with international food-grade safety standards.